The present invention relates to compositions which cure by way of a platinum group metal catalyzed reaction of silicon-bonded hydroxyl radicals and/or silicon-bonded olefinic hydrocarbon radicals with silicon-bonded hydrogen atoms. More specifically, the present invention relates to such curable compositions wherein the room temperature catalytic activity of the platinum group metal catalyst has been greatly inhibited by the presence of an inhibitor component.
Organosilicon compositions in which a platinum group metal catalyst is inhibited in its cure-promoting activity at room temperature by the presence of a catalyst inhibitor are well known in the organosilicon art. Examples of various classes of such metal catalyst inhibitors include unsaturated organic compounds such as ethylenically or aromatically unsaturated amides, U.S. Pat. No. 4,337,332; acetylenic compounds, U.S. Pat. No. 3,445,420; ethylenically unsaturated isocyanates, U.S. Pat. No. 3,882,083; olefinic siloxanes, U.S. Pat. No. 3,989,667; unsaturated hydrocarbon diesters, U.S. Pat. No. 4,256,870; and conjugated eneynes, U.S. Pat. Nos. 4,465,818 and 4,472,563; other organic compounds such as hydroperoxides, sulfoxides, amines, phosphines, phosphites and nitriles; and various metal salts.
While the known platinum group metal catalyst inhibitors are effective for delaying or preventing the room temperature cure of organosilicon compositions which cure by way of a platinum group metal catalyzed reaction, a long-standing problem with the use of such inhibitors still remains.
A continuing problem with inhibited, platinum group metal catalyzed organosilicon compositions is that the cure time and/or the cure temperature of the composition is undesirably increased by the use of an inhibitor. While it is desirable to inhibit or prevent the room temperature cure of such a composition, it is rarely desirable to inhibit the cure of the composition at elevated temperature. This problem is of particular significance for applications where the organosilicon composition is used to rapidly coat a substrate, such as is practiced in the adhesive release coating art.
In the coatings art, such as the paper coating art, the coating composition that is used to coat a substrate should not gel before it has been applied to the substrate; however, it should rapidly cure thereafter, preferably with only a moderate amount of added energy. This means that the coating compositions preferably should not react at ambient temperature for as long as eight hours but should fully cure in less than a few minutes when heated.
The present invention provides organosilicon compositions which have improved room temperature stability and elevated temperature cure rate and which are particularly useful in the coatings art. An inhibitor having unusually stable performance is also provided.